Texas Wastewater Collection System Operator
Class II Exam Test Questions And Correct Answers
(Verified Answers) Plus Rationales 2025/2026 Q&A
| Instant Download Pdf
1. Which of the following is the primary purpose of a wastewater collection
system?
A. To treat wastewater
B. To transport wastewater from homes and businesses to treatment plants
C. To store wastewater indefinitely
D. To purify drinking water
B. To transport wastewater from homes and businesses to treatment
plants
Rationale: The collection system's main role is to move wastewater safely
to treatment facilities, not to treat or store it long-term.
2. The minimum slope required for a 6-inch diameter sanitary sewer pipe to
ensure self-cleaning velocity is approximately:
A. 0.1%
B. 0.5%
C. 1%
D. 2%
C. 1%
, Rationale: A 1% slope ensures sufficient velocity (usually around 2 ft/s) to
prevent sedimentation in small-diameter sewers.
3. Which type of sewer system uses gravity to move wastewater without
pumps?
A. Pressure system
B. Force main system
C. Gravity system
D. Vacuum system
C. Gravity system
Rationale: Gravity systems rely on the natural slope of the land to move
wastewater, reducing energy requirements and mechanical complexity.
4. What is the primary concern when entering a confined space in a collection
system?
A. Excessive noise
B. Hazardous gases and oxygen deficiency
C. Water temperature
D. Electrical conductivity
B. Hazardous gases and oxygen deficiency
Rationale: Confined spaces may contain toxic gases like hydrogen sulfide
or low oxygen levels, posing serious safety risks.
5. The term "inflow" in a wastewater system refers to:
A. Rainwater and groundwater entering the sewer through illegal
connections
B. Wastewater discharged from homes
, C. Treated effluent released from a plant
D. Water used in fire suppression
A. Rainwater and groundwater entering the sewer through illegal
connections
Rationale: Inflow is extra water entering through roof drains, manhole
covers, or other improper connections, which can overload the system.
6. Hydrogen sulfide (H2S) in sewers is primarily produced by:
A. Aerobic bacteria
B. Anaerobic bacteria
C. Chlorine reactions
D. Sulfate removal
B. Anaerobic bacteria
Rationale: Anaerobic bacteria break down organic matter in oxygen-
depleted areas, producing H2S, which is corrosive and toxic.
7. The purpose of a lift station in a collection system is to:
A. Reduce the temperature of wastewater
B. Pump wastewater uphill where gravity flow is insufficient
C. Filter solids from wastewater
D. Treat wastewater chemically
B. Pump wastewater uphill where gravity flow is insufficient
Rationale: Lift stations are used when topography prevents gravity flow,
using pumps to move wastewater to higher elevations.
8. Which of the following is considered a preventative maintenance activity in
sewer systems?
, A. Installing new pumps
B. Cleaning grease traps
C. Flushing and cleaning sewer lines
D. Collecting effluent samples
C. Flushing and cleaning sewer lines
Rationale: Preventative maintenance includes actions like cleaning to
prevent blockages, not reactive repairs or treatment tasks.
9. A sewer blockage is most commonly caused by:
A. Excessive rainfall
B. Grease, roots, and debris
C. High water temperatures
D. Sewer pipe age
B. Grease, roots, and debris
Rationale: These materials accumulate and reduce flow, causing backups
and overflows if not removed regularly.
10.Which method is commonly used to inspect sewer pipelines without
excavation?
A. CCTV camera inspection
B. Manual entry
C. Smoke testing
D. Dye testing
A. CCTV camera inspection
Rationale: Closed-circuit television (CCTV) cameras allow operators to
inspect the interior of sewer pipes efficiently and safely.
Class II Exam Test Questions And Correct Answers
(Verified Answers) Plus Rationales 2025/2026 Q&A
| Instant Download Pdf
1. Which of the following is the primary purpose of a wastewater collection
system?
A. To treat wastewater
B. To transport wastewater from homes and businesses to treatment plants
C. To store wastewater indefinitely
D. To purify drinking water
B. To transport wastewater from homes and businesses to treatment
plants
Rationale: The collection system's main role is to move wastewater safely
to treatment facilities, not to treat or store it long-term.
2. The minimum slope required for a 6-inch diameter sanitary sewer pipe to
ensure self-cleaning velocity is approximately:
A. 0.1%
B. 0.5%
C. 1%
D. 2%
C. 1%
, Rationale: A 1% slope ensures sufficient velocity (usually around 2 ft/s) to
prevent sedimentation in small-diameter sewers.
3. Which type of sewer system uses gravity to move wastewater without
pumps?
A. Pressure system
B. Force main system
C. Gravity system
D. Vacuum system
C. Gravity system
Rationale: Gravity systems rely on the natural slope of the land to move
wastewater, reducing energy requirements and mechanical complexity.
4. What is the primary concern when entering a confined space in a collection
system?
A. Excessive noise
B. Hazardous gases and oxygen deficiency
C. Water temperature
D. Electrical conductivity
B. Hazardous gases and oxygen deficiency
Rationale: Confined spaces may contain toxic gases like hydrogen sulfide
or low oxygen levels, posing serious safety risks.
5. The term "inflow" in a wastewater system refers to:
A. Rainwater and groundwater entering the sewer through illegal
connections
B. Wastewater discharged from homes
, C. Treated effluent released from a plant
D. Water used in fire suppression
A. Rainwater and groundwater entering the sewer through illegal
connections
Rationale: Inflow is extra water entering through roof drains, manhole
covers, or other improper connections, which can overload the system.
6. Hydrogen sulfide (H2S) in sewers is primarily produced by:
A. Aerobic bacteria
B. Anaerobic bacteria
C. Chlorine reactions
D. Sulfate removal
B. Anaerobic bacteria
Rationale: Anaerobic bacteria break down organic matter in oxygen-
depleted areas, producing H2S, which is corrosive and toxic.
7. The purpose of a lift station in a collection system is to:
A. Reduce the temperature of wastewater
B. Pump wastewater uphill where gravity flow is insufficient
C. Filter solids from wastewater
D. Treat wastewater chemically
B. Pump wastewater uphill where gravity flow is insufficient
Rationale: Lift stations are used when topography prevents gravity flow,
using pumps to move wastewater to higher elevations.
8. Which of the following is considered a preventative maintenance activity in
sewer systems?
, A. Installing new pumps
B. Cleaning grease traps
C. Flushing and cleaning sewer lines
D. Collecting effluent samples
C. Flushing and cleaning sewer lines
Rationale: Preventative maintenance includes actions like cleaning to
prevent blockages, not reactive repairs or treatment tasks.
9. A sewer blockage is most commonly caused by:
A. Excessive rainfall
B. Grease, roots, and debris
C. High water temperatures
D. Sewer pipe age
B. Grease, roots, and debris
Rationale: These materials accumulate and reduce flow, causing backups
and overflows if not removed regularly.
10.Which method is commonly used to inspect sewer pipelines without
excavation?
A. CCTV camera inspection
B. Manual entry
C. Smoke testing
D. Dye testing
A. CCTV camera inspection
Rationale: Closed-circuit television (CCTV) cameras allow operators to
inspect the interior of sewer pipes efficiently and safely.
